Water heater control system



Oct. 16, 1945.

C. M. OSTERHELD WATER HEATER CONTROL SYSTEM Filed Jan. 1, 1944 3 sheetssheet 1 [III] III/II INVENTOR. CLARK .05 ZERHZLD My 6 g ATTORNEY Oct.16, 1945. c. M. OSTERHELD WATER HEATER CONTROL SYSTEM 5 Sheet-Sheet 2Filed Jan. 1, 1944 I N V EN TOR. 62 AR%% OSTER/vfll? BY M I III ATTORNEYOct. 16, 1945. c. M. OSTERHELD WATER HEATER CONTROL SYSTEM 3Sheets-Sheet 5 Filed Jan. 1, 1944 CBC s IN V EN TOR. 62 A Gyms a D BYATTORNEY .a control system for a water PatentedOct. 16, 1945 WATERHEATER CONTROL SYSTEM Clark M. Osterheld, Stoughton, Wis., assignor toMeGraw Electric Company, Elgln, lll., a corporation of DelawareApplication January 1, 1944, Serial l do. 516,693

13 Claims.

My invention relates to water heaters and particularly to controlsystems for tank water heaters.

An object of my invention is to limit the maximum energy input into atank.

Another object of my invention is to provide heater to effect selectiveenergization of a plurality of heaters un-' der predetermined conditionsof demand for hot water.

Another object of my invention is to provide a single heater controlswitch mountable on a tank and controlled jointly and simultaneously bytemperature conditions of water throughout the tank.

Other objects of my invention will either be apparent from a,description of a control system embodying my invention or will be setforth in the course of such description and pointed out particularly inthe appended claims.

In the drawings, t

Figure 1 is a verticalseotion of a water tank showing the electriccircuits and contacts when the, water in the top and bottom of the tankis cold,

v Fig. 2 is a fragmentary sectional view taken on the line 2--2 of Fig.1,

Fig. 3 is a fragmentary view showing the position of the contacts whenthe water in the upper part-oi the tank is hot,

Fig. 4 is a fragmentary view showing the position of the contacts whenall of the water in the tank is hot,

Fig. 5 is a top plan view of the parts shown in Fig. '3,

Fig. 6 is a fragmentary end view of the parts shown in Fig. I,

Fig. '7 is a side elevational view of a pluralposition plural-contactheater-control switch,

Fig. 8 is 9, fragmentary sectional View similar to that of Fig. 1showing a modified form'of device embodying my invention, and,

Fig. 9 is an enlarged view of a portion of Fig. 8.

The control system and method of control embodying my invention appliesmore particularly to domestic hot water tanks having an upper and alower heater therefor,the main object of my invention being to socontrol the heaters that there shall always be at least a small quantityof hot water available for immediate use and that the maximum energyinput to heat the water shall be definitely fixed. 1

I have shown a hot water tank It surrounded by heat insulation I3 and anouter casing therearound all in a manner well known in the art. The tankis provided with a lower cold water inlet pipe I! and an upper hot wateroutlet pipe I9 and I may provide also supports 23' all of which are nowwell known in the art.

I provide an upper electric heater 2! and a lower electric heater 21each of which may be positioned around the tank and located in a-tunnel29.

Referring first to Figs. 1 to 7 inclusive I have there shown aplural-contact plural-position heater control switch 3| adapted to beactuated by an upper thermally-expansible rod 33 and a lowerthermally-expansible rod 35. The upper rod 33 has its upper end suitablyfixedly secured as by a bracket 37 to the upper end of the tank whilethe lower rod 35 has its lower end fixedly secured to a bracket 38 whichin turn is fixedly secured against the lower end portion of th tank H.The brackets 31 and 39 are of high-heat conducting material and aresecured in good heatreceiving relation to the tank. The heat-insulatingmaterial 23 is provided with an elongated recess ll for locating the twosubstantially c0- axially aligned rods 33 and 35 which as will be notedfrom Fig. 1 of the drawings'are so mounted as to extend longitudinallyof the tank ii and spaced therefrom. I may provide plates 43 of anysuitable material spaced apart so as to prevent convection currents ofair occurring in the elongated recess 8!. The two rods 33 and 35 aremade of a high expansion material such as alu- The linear temperatureco-efllcient of expansion of aluminum is substantially twice that of theiron or steel .of which the usual domestic hot water tank is made.

The plural-contact plural-position switch 3| is I supported on pivot pin49 in lugs 41. An adjusting screw 53 having a lock nut 55 thereonextends through the horizontalportion of arm 5i and is adapted to engageagainst the lower surface of upper rod 33. l

Frame 45 comprises a vertically upwardly-extending portion 5! having a.pair of lugs 59 ex tending therefrom toward the tank and an arm 6i issupportfid on lugs 5% as by a pivot pin 63. The lower end of arm Si ispivotally connected with a horizontal arm the right hand end portion ofwhich is adapted to move horizontally in a pair of supporting andguiding stirrups 61 and 58 which are connected to or a part of a pair ofspaced horizontal portions 69 of frame $5. The

' upper endof arm 5i is rounded and adapted to The upper end portion ofmember 57 has secured thereon a pair of contacts H, a block 13 ofelectric-insulating material being provided to suitably insulate themfrom frame 35; A first two-part arm 75 is pivotally supported at itslower end adjacent the inner end 'of parts 69 and has insulatedlymounted thereon at its upper end a contact bridging member H. An overcenter spring 19 has its upper end connected to a pivot pin on arm 15,the lower end of spring 19 being suitably secured to a verticallyupwardly-extending lug 8| on arm 65.

A second swinging arm 83 is pivotally mounted adjacent the outer endportion of member 69 and has insulatedly mounted thereon at its upperend a pair of contact members 85, of L-shape. An over center spring 81has its upper end pivotally connected to the, upper end portion of arm83 while its lower end is connected to a lug 89 constituting'a part oforsecured to arm 65.

A stop member for the two arms and 83 includes a horizontally-extendingmember 9i having an inner stop lug 9S and an outer stop lug 95 thereonadapted to be engaged by the arms 15 and 83. Reference to Fig. 7 willshow that the center line of coil spring 19 is closer to the pivot Pointof arm 15 than is the center line of spring 81 from the pivot point ofarm 83. This has "the result that arm 15 will be caused to move overagainst stop lug 93 with a snap action upon movement of arm 65 in aright hand direction, without affecting the second arm. 83. Furtherassure these conditions the design, constructionand adhave used the'words "hot water" hereinafter I refer to water which may have atemperature on the order of say 150 F. For simplicity it may be assumedthat the temperature of the cold water is the usual normal roomtemperature, namely 70 F. The length of the rods 33 and 35 will also bea minimum since they also will have a temperature of substantially 70 F.Under Justment of the expansion rods 33 and 35 and of the plural-contactplural-position heater control switch 3! is such that the parts thereofwill be in the positions shown particularly in Fig. 7 of the drawings,from which it will-be noted that the contact bridging member 11 is inengagement with the contacts H so that the upper heater alone isenergized. This will result in heating up of a relatively small amountof water in the top portion of the tank with the result that thetemperature of the bracket 3'! will be raised from substantially 70 F.to substantially 150 F. with the result that the upper expansion rod 33will. V have its length increased a greater amount than will occur inthe length of the upper portion of the tank with the result that thelower end portion of rod 33 will cause downward movement of adjustingscrew 53 with an attendant turning movement of arm 5| in a clockwisedirection.

This will result in pressure against arm 6| to counteract thetendency ofspring 91, with result ant turning movement of arm 61 in acounterclockwise direction and attendant movement of arm 65 toward theright, as seen in Fig. 7.' It

will be noted that the position of springs I9 and 81 are relativelydifferent so that the right hand movement of arm 65 will cause swingmovement movement of arm 65 in-a right hand direction will cause turningmovement of the second arm 83 with a snap action against stop lug 95.Upon movement of arm 65 in a left hand direction, arm 83 will becausedto move first with arm I5 moving upon further movement of arm 65ina left hand direction. Turning'movement-of arm l5 in a clockwisedirection will cause deenergization of the upper heater 25 andenergization of the lower heater 2! and turning movement of arm 83 in aclockwise direction will cause deenergization of the lower heater 21.

The arm 65 which is adapted to be moved in a straight line axiallythereof is biased into its left hand limiting position by a spring 9?,and

a pair of rollers 98 are provided in portion to to permit of easymovement of bar 65.

I provide a bracket 99 which may be secured against the outside of thetank by screws iill extending into metallic blocks H33, heat-insu-=lating'material 905 being provided 'therebetween of arm 15 in a.clockwise direction before swinging movement of arm 83 will occur. Thiswill cause engagement of contact bridging member 11 with the two contactterminals 85 with the result that the upper .heater 25 is 'deenergizedbut the lower heater 2! is energized. The diagram of connections isshownin Fig. 1, which shows twosupply circuit conductors W9 and 'l i i.

Heating oi the rest of the water in the tank H will continue untilsubstantially all of the water in the tank is hot. When this occurs thetemperature of bracket 39 will also be on the order of substantially 150F. with the result that the temperature of the lower expansion rod 35will also be on the order of 150 F. with consequent iii? to suitablyheat-insulate the bracket 99 -fromi the temperature of the tank water.The bracket is provided with lateral extensions ltl at its upper andlower ends, having apertures therein to receive the rods 33 and 35 tomaintain them in alignment, it being understood that the rods may movelongitudinally in the portions till.

Let it be assumed that the tank has been filled with cold Water, inwhich case the longitudinal dimension of the tank will be a minimumrelative to its dimension afterwards when substantially all of the waterin the tank has been heated to a predetermined temperature. Where Iincrease in length of expansion rod 35. I

The result of this expansion of rod 35h that arm at is caused to turn ina clockwise direction still further with resultant turning movement oiaunt! in a counter-clockwise direction and further right hand movementof' arm 65. When arm 68 has been moved against spring at suificlently sothat the lower end of spring 31 has been moved beyond the pivot point ofarm 33, the arm 83 will turn in a clockwise direction against stop sothat the lower heater 2'! is deenergized by reason of the disengagementof contact terminals $5 from contact bridging member ll.

It is thus evident that the singleplural-contact plural-position switchis actuated jointly and simultaneously by the two expansion rods 33 and35 which, are subject to the thermal conditions of the water in theupper and in the lower parts of the tank so as to energize the upperheater only when all of the water in the tank is cold until such time asa partof the water in the upper-portion of the tank has been heatedafter which the upper heater is deenergized and the lower heater isenergized until substantially all of the water in the tank is hot.

Referring now to Figs. 8 and 9 of the drawings I have there illustrateda modification ofthecontrol system shown inFigs. l to 7 and embodying myinvention and have shown an upper rod H3 and a lower rod H securedfixedly respectively .at the uppe end of the upper rod against the upperend portion of the tank as by a bracket I I? and the lower end of thelower red as by a bracket H3. Rods H3 and iii are of non-expansiblematerial or alloy such as Invar. The switch 3i is secured to the upperend portion of rod H5 as by a member 44 and an L-shaped lever arm III ispivotally mounted intermediate the horizontal part thereof on lugs I 23.The lower face of the upper rod H3 has secured thereto a depending lugI25 having pivotal engagement with the left hand end portion of thehorizontal arm there will be a tendency for arm i2! to be turned in aclockwise direction with attendant move-v ment or arm Si in acounter-clockwise, direction and movement of arm 65 toward the right.When arm 65 and particularly spring 19 have, been moved sufliciently tothe right so that the lower portion of spring 19 has been movedhorizontally beyond the pivot point of arm (5, arm 15 will be moved in aclockwise direction, resulting in disengagement of bridging member 11from contact terminal II with deenergization of the upper heaterrContact bridging member 11 has been moved into electrical engagementwith contact terminals 85 on arm 83 sorthat lower heater 21 in nowenergized.

When substantially all of the water in the tank has been heated to say150 F., the entire length of tank H is such that arm i2l will have beenturned sufficiently in clockwise direction to cause further slidingmovement of arm 65 toward the right so that arm 83 will have been turnedin a clockwise direction against stop 95 with the result ofdisengagement of terminals 85 from bridging member I1 and resultantdeenergization of the lower heater 21. The arm 15 is prevented fromfollowing the arm 83 by contacting the stop 93.

If it be assumed that hot water is demanded and a relatively smallamount is used, say about one-third of a tank full, arm 65 will becaused to move toward the left suffici'ently to cause swinging movementof arm 83 in a counter-clockwise direction to bring terminals 85 againin engagement with contact bridging member 11 whereby the lower heater2! will again be energized, this energization continuing untilsubstantially all of the water in the tank has again been heated to say150 F. when bar 65 will be moved to the right to cause deenergization ofthe lower heater 21.

I am aware of other patents showing a very different control system foran upper and a lower tank heater comprising a control switch thermallyactuated in accordance with the temperature of the water in the upperend portion of the tank and controlling not only the upper heater butalso the lower heater. The lower heater is also provided with athermally-actuable' switch. In contradistinction to this system I maypoint out that my improved system includes a single plural-contactplural-position switch and two rod members, one of which supports theswitch, the two red members having their outer ends fixedly secured toend portions of the tank, the inner end portions' of the rods extendingsubstantially closely toward each other, relative movement of the endsof said rods occurring as a consequence of the different thermal linearexpansion of the two rods and of the tank when the tank is filled withcold water or filled with hot water,v

The device and system embodying my invention therefore provides arelatively simple control system and switch efiective for the desiredpurpose of limiting the energy input into a tank and of alwaysmaintaining available for immediate use at least a predetermined amountof hot water.

Various modifications may be made in the device and system embodying myinvention and all modifications thereof coming clearly within the scopeof the appended claims are to be considere a part thereof.

I claim as my invention:

I l. A water heater control system for a hot water tank having an upperand a lower electric heater for said tank, a single plural-contactplural-position switch for selectively controlling the energization ofsaid heaters, an upper rod having its upper end secured fixedly to theupper end portion of said tank, a lower rod having its lower end securedfixedly to the lower end portion of said tank, said rods extendinglongitudinally of said tank with their inner ends spaced apart, andhaving difierent linear thermal expansion than said tank, meanssupporting said switch on the inner end of one of said rods andswitchactuating means engaged by the inner end of the other rod forcausing movement of said switch into a position to eilect deenergizationof the lower heater and energization of said upper heater when the tankis substantially full of cold water.

2. A water heater control system for a hot water tank having an upperand a lower electric heater for said tank, a single plural-contactplural-position switch for selectively controlling the energization ofsaid heaters, an upper rod having its upper end secured fixedly to theupper end portion of said tank, a lower rod having its lower end securedfixedly to the lower end portion of said tank, said rods extendinglongitudinally of said tank with their inner ends spaced apart, saidrods having difierent linear thermal expansion than said tank, meanssupporting said switch on the inner end of one of said rods andswitch-actuating means engaged by the inner end of the other rod forcausing movement of said switch into a position to effect deenergizationof the lower heater and energization of said upper heater when the tankis substantially full of cold water andto efiect deenergization of saidupper heater and energization of said lower heater when the tankcontains a predetermined quantity of hot water in the upper portionthereof.

3. A water heater control system for a hot water tank having an upperand a lower electric heater for said tank, a single plural-contactplural-position switch for selectively controlling the energization ofsaid heaters, an upper rod having its upper end secured fixedly to theupper end portion of said tank, a lower rod having its lower end securedfixedly to the lower end portion of said tank, said rods extendinglongitudinally or said tank with their inner ends spaced apart andhaving different linear thermal expansion than said tank, meanssupporting said switch on the inner end of one of said rods andswitch-actuating means engaged by the inner end of the other rod forcausing movement or" said switch into a position to efiectdeenergization of the lower heater and energization of said upper heaterwhen the tank is substantially full of cold water and to eiiectdeenergization of said upper heater and energlzation of'said lowerheater when the tank contains a predetermined quantity of hot water inthe upper portion thereof and to effect deenergization of said lowerheater when the tank is substantially full of hot water.

i. A water heater control system for a hot water tank having an upperand a lower electric heater therefor, a single plural-contactthree-position switch for selectively controlling said heaters, a pairof rods having different linear thermal expansion than said tank, thelength of each rod being slightly less than one-half of the length ofthe tank, extending longitudinally of the tank with the outer endsfixedly secured to the end portions of the tank, said rods jointlycontrolling said being slightly less than one-half of the length of thetank, extending longitudinally of the tank with the outer ends fixedlysecured to the end portions of the tank, said rods jointly controllingsaid switch in accordance with the temperature of the water throughoutthe tank to cause ener gization of the upper heater only, when the tankis full of cold water and to cause deenergization of the upper heaterand energization of the lower heater when a predetermined part of thewater in the tank has been heated-to a predetermined temperature.

6. A water heater control system for a hot water tank having an upperand a lower electric heater therefor, a single plural-contact threep0-sition switch for selectively controlling said heaters, a pair of rodshaving different linear thermal expansion than said tank, the length ofeach rod being slightly less than one-half of the length of the tank,extending longitudinally of the tank with the outer ends fixedly securedto the end portions of the tank, said rods jointly controlling saidswitch in accordance with the temperature of the water throughout thetank to cause energization of the upper heater only when the tank isfull of cold water and to cause deenergization of the upper heater andenergization of the lower heater when a predetermined part of the Waterin the tank has been heated to a predetermined tembeing slightly lessthan one-half o1" the length of the. tank, extending longitudinally ofthe tank with the outer ends fixedly secured to the end portions of thetank, said rod jointly controlling said switch in accordance with thetemperature of the water throughout the tank to cause energize.- tionof. the upper heater only when the tank is full of cold water and tocause deenergization of the upper heater and energization of the lowerheater when a predetermined part of the water in the tank has beenheated to a predetermined temperature and to cause deenergization of thelower heater when substantially all of the water in the tank has beenheated to a predetermined temperature and to cause reenergization ofsaid lower heater in case of withdrawal of a predetermined relativelysmall amount of hot water from the tank. 1.

8. A water heater control system for a hot water tank having an upperand a lower electric v heater therefor, a single plural-contactthree-position switch for selectively controlling said heaters, a pair02 rods having diiierent linear thermal expansion than said tank, thelength of each rod being slightly less than one-half of the length.

of the tank, extending longitudinally of the tank with the outer endsfixedly secured to the end portions of the tank, said rods jointlycontrolling said switch in accordance with the temmrature of the waterthroughoutthe tank to cause energization of the upper heater only whenthe tank is full of cold water and to cause deenergization of the upperheater and energization of the lower heater when a predetermined part ofthe water in the tank has been heated toa predetermined temperature andto cause deenergization of the lower heater when substantially all ofthewater in the tank has been heated to a predetermined temperature andto cause reenergization of said upper heater only in case of withdrawalof a predetermined relatively large amount of hot water from the tank.

9. A water heater control system for a bottleter tank, having a coldwater inlet at its lower end and a hot water outlet at its upper end andan upper and a lower electric heater, comprisperature and to causedeenergiz'ation of the lower heater when substantially all of the waterin the tank ha been heated to a predetermined tem-= perature.

7. A water heater control system for a hotwater-tank having an upper anda lower electric ers, a pair of rods having. difierent linear thermalexpansion than said tank, the length or each rod heater therefor, asingle plural-contact three-po v sition switch for selectivelycontrolling said heating a single plural-contact three-position switchfor selectively controlling said heaters and means for'actuating saidswitch comprising an upper rod having its upper end fixedly secured tothe upper end of the tank, a lower rod having its lower end fixedlysecured to the lower end of the tank, said rods extending longitudinallyof said tank with their inner ends spaced apart, said rods having alinear thermal expansion difierent than that of the tank, meanssupporting said switch on the inner end of one of said rods andswitch-actuating means engaged by the inner end of the other rod forcausin movement of said switch into a position to eficct energization ofsaid upper heater only when the tank is substantially full of coldwater. I

10. A water heater control system for a hot water tank having a coldwater inlet at its lower end and a hot water outlet at its upper end andan. upper and a lower electric heater, comprising asingle-plural-contact three-position switch for selectively controllingsaid heaters and means for actuating said switch comprising an upper rodhaving its upper end fixedly secured to the upper end of the tank, alower rod having its lower end fixedly secured to the lower'end of thetank, said rods extending longitudinally of said tank with their innerends spacedapart, said rods having a linear thermal expansion difierentthan that i; i l

of cold water and to cause deenergization of the upper heater andenergization of the lower heater when a predetermined part of the water.in the tank has been heated toa predetermined temperature.

11. A water heater control system for a hot water tank having a coldwater inlet at its lower assigns end and a hot water outlet at its upperend and an upper and a lower electric heater, comprising a singleplural-contact three-position switch for selectively controlling saidheaters and means for actuating said switch comprising an upper rodhaving its upper end fixedly secured to the upper end of the tank, alower rod having its lower end fixedly secured, to the lower end 01 thetank, said rods extending longitudinally of saidfltank with their innerends spaced apart, said rods having a linear thermal expansion greaterthan that of the tank, means supporting said switch on the inner end ofone of said rods and switch actuating means engaged by the inner end orthe other rod for causing movement of said switch into a position toeflect energization of said upper heater only when the tank issubstantially full of cold-water and to cause deenergization of theupper heater and 'energization of the lower heater when a predeterminedpart of the water in the tank has been heated to a predeterminedtemperature and to cause deenergization of the lower heater whensubstantially all of the water in the tank has been heated to apredetermined temperature.

12. A water heater control system for a hot water tank having a coldwater inlet at its lower end and a hot water outlet at its upper end andactuating said switch comprising an upper rod having its upper endfixedly secured to the upper end of the tank, a lower rod having itslower end fixedly secured to the lower end of the tank,

said rods. extending longitudinally oi said tank with their inner endsspaced apart, said rods having a linear thermal expansion less than thatof the tank, means supporting said switch on the inner end of one 01'said rods and switch-actuating means engaged by the inner end of theother rod for causing movement of said switch into a position to eflectenergization of said upper heater only when the tank is substantiallyfull of cold water and to cause deenergization of the upper heater andenergization of the lower heater when a predetermined part of the waterin the tank has been heated to a predetermined temperature and to causedeenergization or the lower heater when substantially all of the waterin the tank has been heated to a predetermined temperature and to causereenergization of said lower heater in case of withdrawal of apredetermined relatively small amount of hot water from the tank.

13. A water heater controlsystem for a hot water tank having a coldwater inlet at its lower end and a hot water outlet at its upper end andan upper and a lower electric heater, comprising a single plural-contactthree-position switch for selectively controlling said heaters and meansfor actuating said switch comprising an upper rod having its upper endfixedly secured to the upper end of the tank, a lower rod having itslower end fixedly secured to the lower end of the tank, said rodsextending longitudinally of said tank with their inner ends spacedapart, said rods having a linear thermal expansion greater than that ofthe tank, means supporting said switch on the inner end of the lower of,said rods and switchactuating means engaged by the inner end of theupper: rod for causing movement of said switch into a position to effectenergization of said upper heater only when the tank is substantiallyfull of cold water. i

' CLARK M. OS'I'ERHELD.

